While much is now known about the mechanisms of proprioception in crustacean limbs, there has been little attention paid to the central utilization of this information in the control of movement and position of the limbs. The aim of this project is to assess the role of proprioceptive feedback in the central nervous system and to determine its interactions with other signals impinging on the motor centers controlling limb movement. Thus, assuming resistance reflexes to be the simplest level of control, in what manner do other centrally-originated inputs to the motor center interact with these reflexes to produce a coordinated movement of the limb. This problem will be approached by utilizing chronic recording techniques which permit monitoring of motoneuron output in intact, behaving animals. Since, in certain crustacea, one can identify reflex output by the time distribution of motor activity it will be possible to determine what fraction of output is due to reflexes and what is due to centrally-originated inputs. When these recordings are synchronized with motion picture records of limb movements, the result will be a complete record of movement and motor output. Thus, by recording under various conditions, the final result will be a set of interactions between reflexes, other external stimuli and centrally-originated behavior. These interactions will then permit an hypothesis, based on quasi-normal behavior, to explain the central nervous interactions among these various information pathways.